1. Field of the Invention
The present invention is directed, in general, to video optimization, and more particularly to a method for deriving an objective metric for evaluating sharpness of video sequences.
2. Description of the Related Art
Sharpening is performed in order to improve the picture quality of an image. As such, sharpness is an image attribute that is clearly identified by the human visual system (HVS). The HVS can easily grade an image as being ‘unsharp’, ‘normally sharp’, ‘very sharp’ or ‘unnaturally sharp’. Up to a certain level of sharpness, the HVS perceives the picture as more pleasing. However, beyond a certain sharpness level, the picture starts to look unnatural. If the sharpness is increased even further, the picture starts to exhibit artifacts like saturation, aliasing, false edges, etc. At this point, the image becomes subjectively intolerable. Clearly, there exists a relationship between the sharpness level of an image and the HVS.
It would therefore be desirable to objectively characterize the relationship between the sharpness level of an image and the HVS so as to develop an objective quality metric. The metric could find application, for example, in an automated video optimization chain.